An emulsion consists of two immiscible liquids mixed together with small droplets of one liquid dispersed in the other liquid. The dispersion is usually not stable and all the droplets “clump” together over time to form two layers. An emulsion can be stabilized by inhibiting coalescence (i.e., preventing the droplets from clumping together) by the presence of surfactant molecules. The majority of emulsions can be classified according to the chemical nature of the liquids, such as oil-in-water (O/W) or water-in-oil (W/O).
O/W emulsions are widely used in the cosmetic and other industries due to their sensorial profile characterized by light skin feel, non-greasy texture, and high spreadability index, as well as for their easy production methods. Gel-in-water systems (water gels) having similar sensorial characteristics can be achieved using a thickening agent (e.g., acrylate polymers) mixed with water. Acrylate polymers are also able to produce O/W emulsions, and, in general, stable O/W emulsions require ionic surfactants or a non-ionic ethoxylated/propoxylated product. However, the presence of ionic surfactants can lead to skin sensitization and skin irritation, and the presence of acrylate polymers, ethoxylated and propoxylated products are not desirable to produce “green” (environmentally-friendly) emulsions. Thus, there exists a need for O/W emulsions and water gels lacking ionic surfactants, acrylate polymers, ethoxylated or propoxylated emulsifiers.
The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.